Field of the Invention
This invention relates to locks for windows and more particularly to locks for a window with sliding sashes.
Description of the Prior Art
In most sliding sash window installations, the window locks are placed on the top rail of the lower sash, visible to the outside and easily turned if the pane is broken. The conventional window lock is also "easily" broken by prying at the window. Many devices have been devised to make a safer window lock either by concealing it or by requiring a key for unlocking it. Many of these devices use a housing in the window sash into which a rod is inserted. Alpern (U.S. Pat. No. 3,642,315) uses a second magnetized rod to remove the first rod. Kirkpatrick (U.S. Pat. No. 1,580,611), Kistner (U.S. Pat. No. 2,076,847) and Bishop (U.S. Pat. No. 3,501,932) employ rods inserted into housings having springs, and are all unlocked with flat keys which engage slots in the proximate rod end.
Glatt (U.S. Pat. No. 2,537,049) uses a preinserted rod/bolt in a window channel which is screwed into and out of a locking position by a key. Turney (U.S. Pat. No. 1,396,478) is another rod-like lock which requires a housing for the rod. Clompus (U.S. Pat. No. 4,351,170) also uses a key operated bolt which is inserted into a plug placed on overlapping window portions.
Phelps (U.S. Pat. No. 4,068,506) has a hollow tube lock concealed in channels in overlapping window sashes. The tube is removed by a key inserted into slots in the wall of the tube. The ends of the tube are straight cylinder ends.
With Phelps' device and with many of the previously mentioned devices, it is difficult to align the predrilled window channels in such a manner as to allow easy insertion of the rod. If the window channels are not exactly aligned to each other, the flat end of Phelps' lock (for an example) will not slide directly into the channel in the second window member. Yet, if the channels are drilled much larger than the rod, the rod will come out without needing the key.
There is therefore a need for a concealed window lock which combines security with ease of operation, which requires no installation of housing for the lock, and which will be easily inserted and removed from predrilled window channels.